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Keith SA, Hobbs JP, Boström-Einarsson L, Hartley IR, Sanders NJ. Rapid resource depletion on coral reefs disrupts competitor recognition processes among butterflyfish species. Proc Biol Sci 2023; 290:20222158. [PMID: 36598015 PMCID: PMC9811634 DOI: 10.1098/rspb.2022.2158] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Avoiding costly fights can help conserve energy needed to survive rapid environmental change. Competitor recognition processes help resolve contests without escalating to attack, yet we have limited understanding of how they are affected by resource depletion and potential effects on species coexistence. Using a mass coral mortality event as a natural experiment and 3770 field observations of butterflyfish encounters, we test how rapid resource depletion could disrupt recognition processes in butterflyfishes. Following resource loss, heterospecifics approached each other more closely before initiating aggression, fewer contests were resolved by signalling, and the energy invested in attacks was greater. By contrast, behaviour towards conspecifics did not change. As predicted by theory, conspecifics approached one another more closely and were more consistent in attack intensity yet, contrary to expectations, resolution of contests via signalling was more common among heterospecifics. Phylogenetic relatedness or body size did not predict these outcomes. Our results suggest that competitor recognition processes for heterospecifics became less accurate after mass coral mortality, which we hypothesize is due to altered resource overlaps following dietary shifts. Our work implies that competitor recognition is common among heterospecifics, and disruption of this system could lead to suboptimal decision-making, exacerbating sublethal impacts of food scarcity.
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Affiliation(s)
- S. A. Keith
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - J-P.A. Hobbs
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4069, Australia
| | | | - I. R. Hartley
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - N. J. Sanders
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
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2
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Gunn RL, Hartley IR, Algar AC, Nadiarti N, Keith SA. Variation in the behaviour of an obligate corallivore is influenced by resource availability. Behav Ecol Sociobiol 2022. [DOI: 10.1007/s00265-022-03132-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Abstract
Marine environments are subject to increasing disturbance events, and coral reef ecosystems are particularly vulnerable. During periods of environmental change, organisms respond initially through rapid behavioural modifications. Whilst mean population level modifications to behaviour are well documented, how these shifts vary between individuals, and the relative trade-offs that are induced, are unknown. We test whether the frequency and time invested in different behaviours varies both between and within individuals with varying resource availability. To do this, we quantify differences in four key behavioural categories (aggression, exploration, feeding and sociability) at two sites of different resource availability, using an obligate corallivore butterflyfish species (Chaetodon lunulatus). Individuals on a low resource site held larger territories, investing more time in exploration, which was traded off with less time invested on aggression, feeding and sociability. Repeatability measures indicated that behavioural differences between sites could plausibly be driven by both plasticity of behaviour within individuals and habitat patchiness within feeding territories. By combining population-level means, co-correlation of different behaviours and individual-level analyses, we reveal potential mechanisms behind behavioural variation in C. lunulatus due to differences in resource availability.
Significance statement
Using observational methods, we identify differences in the behaviour of an obligate corallivorous butterflyfish (Chaetodon lunulatus) between a high and a low resource site. We use a combination of density surveys, territory mapping and behavioural observation methods in a comparative analysis to relate behaviour directly to the environment in which it occurs. Bringing together insights from game theory and optimal foraging, we also use our results to highlight how understanding the correlations of different behaviours can inform our understanding of the extent to which behaviours are plastic or fixed. Furthermore, by considering how multiple behaviours are correlated, we move away from exploring individual behaviours in isolation and provide an in-depth insight into how differences in behaviour both between individuals and at the population level can affect responses to declining resource availability.
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3
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MacDonald C, Pinheiro HT, Shepherd B, Phelps TAY, Rocha LA. Disturbance and distribution gradients influence resource availability and feeding behaviours in corallivore fishes following a warm-water anomaly. Sci Rep 2021; 11:23656. [PMID: 34880357 PMCID: PMC8654952 DOI: 10.1038/s41598-021-03061-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 11/24/2021] [Indexed: 11/09/2022] Open
Abstract
Understanding interactions between spatial gradients in disturbances, species distributions and species’ resilience mechanisms is critical to identifying processes that mediate environmental change. On coral reefs, a global expansion of coral bleaching is likely to drive spatiotemporal pulses in resource quality for obligate coral associates. Using technical diving and statistical modelling we evaluated how depth gradients in coral distribution, coral bleaching, and competitor density interact with the quality, preference and use of coral resources by corallivore fishes immediately following a warm-water anomaly. Bleaching responses varied among coral genera and depths but attenuated substantially between 3 and 47 m for key prey genera (Acropora and Pocillopora). While total coral cover declined with depth, the cover of pigmented corals increased slightly. The abundances of three focal obligate-corallivore butterflyfish species also decreased with depth and were not related to spatial patterns in coral bleaching. Overall, all species selectively foraged on pigmented corals. However, the most abundant species avoided feeding on bleached corals more successfully in deeper waters, where bleaching prevalence and conspecific densities were lower. These results suggest that, as coral bleaching increases, energy trade-offs related to distributions and resource acquisition will vary with depth for some coral-associated species.
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Affiliation(s)
- Chancey MacDonald
- Department of Ichthyology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA, 90118, USA.
| | - Hudson T Pinheiro
- Department of Ichthyology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA, 90118, USA.,Center of Marine Biology, University of São Paulo, Rod. Dr. Manoel Hipólito do Rego, km 131.5, São Sebastião, SP, 11612-109, Brazil
| | - Bart Shepherd
- Steinhart Aquarium, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA, 90118, USA
| | - Tyler A Y Phelps
- Department of Ichthyology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA, 90118, USA.,Department of Biology, San Francisco State University, 1600 Holloway Ave, San Francisco, CA, 94132, USA
| | - Luiz A Rocha
- Department of Ichthyology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA, 90118, USA
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4
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Martorell-Barceló M, Mulet J, Sanllehi J, Signaroli M, Lana A, Barcelo-Serra M, Aspillaga E, Alós J. Aggressiveness-related behavioural types in the pearly razorfish. PeerJ 2021; 9:e10731. [PMID: 33850638 PMCID: PMC8018250 DOI: 10.7717/peerj.10731] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 12/17/2020] [Indexed: 11/20/2022] Open
Abstract
Behavioural types (i.e., personalities or temperament) are defined as among individual differences in behavioural traits that are consistent over time and ecological contexts. Behavioural types are widespread in nature and play a relevant role in many ecological and evolutionary processes. In this work, we studied for the first time the consistency of individual aggressiveness in the pearly razorfish, Xyrichtys novacula, using a mirror test: a classic method to define aggressive behavioural types. The experiments were carried out in semi-natural behavioural arenas and monitored through a novel Raspberry Pi-based recording system. The experimental set up allowed us to obtain repeated measures of individual aggressivity scores during four consecutive days. The decomposition of the phenotypic variance revealed a significant repeatability score (R) of 0.57 [0.44-0.60], suggesting high predictability of individual behavioural variation and the existence of different behavioural types. Aggressive behavioural types emerged irrespective of body size, sex and the internal condition of the individual. Razorfishes are a ubiquitous group of fish species that occupy sedimentary habitats in most shallow waters of temperate and tropical seas. These species are known for forming strong social structures and playing a relevant role in ecosystem functioning. Therefore, our work provides novel insight into an individual behavioural component that may play a role in poorly known ecological and evolutionary processes occurring in this species.
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Affiliation(s)
- Martina Martorell-Barceló
- Fish Ecology Group, Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB), Esporles, Spain
| | - Júlia Mulet
- Fish Ecology Group, Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB), Esporles, Spain.,Universitat de Barcelona, Barcelona, Spain
| | - Javier Sanllehi
- Fish Ecology Group, Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB), Esporles, Spain
| | - Marco Signaroli
- Fish Ecology Group, Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB), Esporles, Spain
| | - Arancha Lana
- Fish Ecology Group, Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB), Esporles, Spain
| | - Margarida Barcelo-Serra
- Fish Ecology Group, Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB), Esporles, Spain
| | - Eneko Aspillaga
- Fish Ecology Group, Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB), Esporles, Spain
| | - Josep Alós
- Fish Ecology Group, Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB), Esporles, Spain
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5
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Baraf LM, Pratchett MS, Cowman PF. Ancestral biogeography and ecology of marine angelfishes (F: Pomacanthidae). Mol Phylogenet Evol 2019; 140:106596. [DOI: 10.1016/j.ympev.2019.106596] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 08/13/2019] [Accepted: 08/13/2019] [Indexed: 12/27/2022]
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6
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MacDonald C, Bridge TCL, McMahon KW, Jones GP. Alternative functional strategies and altered carbon pathways facilitate broad depth ranges in coral‐obligate reef fishes. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13400] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chancey MacDonald
- Marine Biology and Aquaculture Science, College of Science and Engineering James Cook University Townsville Qld Australia
- Australian Research Council Centre for Excellence in Coral Reef Studies James Cook University Townsville Qld Australia
| | - Tom C. L. Bridge
- Australian Research Council Centre for Excellence in Coral Reef Studies James Cook University Townsville Qld Australia
- Biodiversity and Geosciences Program, Museum of Tropical Queensland Queensland Museum Network Townsville Qld Australia
| | - Kelton W. McMahon
- Institute of Marine Sciences University of California – Santa Cruz Santa Cruz CA USA
- Graduate School of Oceanography University of Rhode Island Narragansett RI USA
| | - Geoffrey P. Jones
- Marine Biology and Aquaculture Science, College of Science and Engineering James Cook University Townsville Qld Australia
- Australian Research Council Centre for Excellence in Coral Reef Studies James Cook University Townsville Qld Australia
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7
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St. John ME, McGirr JA, Martin CH. The behavioral origins of novelty: did increased aggression lead to scale-eating in pupfishes? Behav Ecol 2019; 30:557-569. [PMID: 30971862 PMCID: PMC6450202 DOI: 10.1093/beheco/ary196] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 11/08/2018] [Accepted: 12/14/2018] [Indexed: 11/13/2022] Open
Abstract
Behavioral changes in a new environment are often assumed to precede the origins of evolutionary novelties. Here, we examined whether an increase in aggression is associated with a novel scale-eating trophic niche within a recent radiation of Cyprinodon pupfishes endemic to San Salvador Island, Bahamas. We measured aggression using multiple behavioral assays and used transcriptomic analyses to identify differentially expressed genes in aggression and other behavioral pathways across 3 sympatric species in the San Salvador radiation (generalist, snail-eating specialist, and scale-eating specialist) and 2 generalist outgroups. Surprisingly, we found increased behavioral aggression and differential expression of aggression-related pathways in both the scale-eating and snail-eating specialists, despite their independent evolutionary origins. Increased behavioral aggression varied across both sex and stimulus context in both species. Our results indicate that aggression is not unique to scale-eating specialists. Instead, selection may increase aggression in other contexts such as niche specialization in general or mate competition. Alternatively, increased aggression may result from indirect selection on craniofacial traits, pigmentation, or metabolism-all traits which are highly divergent, exhibit signs of selective sweeps, and are affected by aggression-related genetic pathways which are differentially expressed in this system. In conclusion, the evolution of a novel predatory trophic niche within a recent adaptive radiation does not have clear-cut behavioral origins as previously assumed, highlighting the multivariate nature of adaptation and the complex integration of behavior with other phenotypic traits.
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Affiliation(s)
| | - Joseph A McGirr
- Department of Biology, University of North Carolina at Chapel Hill, NC, USA
| | - Christopher H Martin
- Department of Biology, University of North Carolina at Chapel Hill, NC, USA
- Department of Integrative Biology and Museum of Vertebrate Zoology, University of California, Berkeley, CA, USA
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8
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Pair bond endurance promotes cooperative food defense and inhibits conflict in coral reef butterflyfish. Sci Rep 2018; 8:6295. [PMID: 29674741 PMCID: PMC5908845 DOI: 10.1038/s41598-018-24412-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 04/03/2018] [Indexed: 11/08/2022] Open
Abstract
Pair bonding is generally linked to monogamous mating systems, where the reproductive benefits of extended mate guarding and/or of bi-parental care are considered key adaptive functions. However, in some species, including coral reef butterflyfishes (f. Chaetodonitidae), pair bonding occurs in sexually immature and homosexual partners, and in the absence of parental care, suggesting there must be non-reproductive adaptive benefits of pair bonding. Here, we examined whether pair bonding butterflyfishes cooperate in defense of food, conferring direct benefits to one or both partners. We found that pairs of Chaetodon lunulatus and C. baronessa use contrasting cooperative strategies. In C. lunulatus, both partners mutually defend their territory, while in C. baronessa, males prioritize territory defence; conferring improvements in feeding and energy reserves in both sexes relative to solitary counterparts. We further demonstrate that partner fidelity contributes to this function by showing that re-pairing invokes intra-pair conflict and inhibits cooperatively-derived feeding benefits, and that partner endurance is required for these costs to abate. Overall, our results suggest that in butterflyfishes, pair bonding enhances cooperative defense of prey resources, ultimately benefiting both partners by improving food resource acquisition and energy reserves.
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9
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Nowicki JP, O’Connell LA, Cowman PF, Walker SPW, Coker DJ, Pratchett MS. Variation in social systems within Chaetodon butterflyfishes, with special reference to pair bonding. PLoS One 2018; 13:e0194465. [PMID: 29641529 PMCID: PMC5894994 DOI: 10.1371/journal.pone.0194465] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 03/02/2018] [Indexed: 11/18/2022] Open
Abstract
For many animals, affiliative relationships such as pair bonds form the foundation of society and are highly adaptive. Animal systems amenable for comparatively studying pair bonding are important for identifying underlying biological mechanisms, but mostly exist in mammals. Better establishing fish systems will enable comparison of pair bonding mechanisms across taxonomically distant lineages that may reveal general underlying mechanistic principles. We examined the utility of wild butterflyfishes (f: Chaetodontidae; g: Chaetodon) for comparatively studying pair bonding. Using stochastic character mapping, we provide the first analysis of the evolutionary history of butterflyfish sociality, revealing that pairing is ancestral, with at least seven independent transitions to gregarious grouping and solitary behavior since the late Miocene. We then formally verified social systems in six sympatric and wide-spread species representing a clade with one ancestrally reconstructed transition from paired to solitary grouping at Lizard Island, Australia. In situ observations of the size, selective affiliation and aggression, fidelity, and sex composition of social groups confirmed that Chaetodon baronessa, C. lunulatus, and C. vagabundus are predominantly pair bonding, whereas C. rainfordi, C. plebeius, and C. trifascialis are predominantly solitary. Even in the predominantly pair bonding species, C. lunulatus, a proportion of adults (15%) are solitary. Importantly, inter- and intra-specific differences in social systems do not co-vary with other previously established attributes, including parental care. Hence, the proposed butterflyfish populations are promising for inter- and intra-species comparative analyses of pair bonding and its mechanistic underpinnings. Avenues for further developing the system are proposed, including determining whether the aforementioned utility of these species applies across their geographic disruptions.
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Affiliation(s)
- Jessica P. Nowicki
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
- Department of Biology, Stanford University, Stanford, California, United States of America
- * E-mail: (JPN); (MSP)
| | - Lauren A. O’Connell
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Peter F. Cowman
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
| | - Stefan P. W. Walker
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
| | - Darren J. Coker
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Morgan S. Pratchett
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
- * E-mail: (JPN); (MSP)
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10
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Pratchett MS, Thompson CA, Hoey AS, Cowman PF, Wilson SK. Effects of Coral Bleaching and Coral Loss on the Structure and Function of Reef Fish Assemblages. ECOLOGICAL STUDIES 2018. [DOI: 10.1007/978-3-319-75393-5_11] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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11
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Blowes SA, Pratchett MS, Connolly SR. Aggression, interference, and the functional response of coral-feeding butterflyfishes. Oecologia 2017; 184:675-684. [PMID: 28669003 DOI: 10.1007/s00442-017-3902-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 06/20/2017] [Indexed: 11/26/2022]
Abstract
Functional responses describing how foraging rates change with respect to resource density are central to our understanding of interspecific interactions. Competitive interactions are an important determinant of foraging rates; however, the relationship between the exploitation and interference components of competition has received little empirical or theoretical consideration. Moreover, little is known about the relationship between aggressive behavioural interactions and interference competition. Using a natural gradient of consumer and resource densities, we empirically examine how aggressiveness relates to consumer-consumer encounter rates and foraging for four species of Chaetodon reef fish spanning a range of dietary niche breadths. The probability of aggression was most strongly associated with both total consumer and resource densities. In contrast, total encounter rates were best predicted by conspecific consumer density, and were highest for the most specialised consumer (Chaetodon trifascialis), not the most aggressive (Chaetodon baronessa). The most specialised consumer, not the most aggressive, also exhibited the largest reduction in foraging rates with increasing consumer density. Our results support the idea of a positive link between the exploitation and interference components of competition for the most specialised consumer. Moreover, our results caution against inferring the presence of ecological interactions (competition) from observations of behaviour (aggression and agonism) alone.
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Affiliation(s)
- Shane A Blowes
- Marine Biology and Aquaculture, College of Science and Engineering, James Cook University, Townsville, QLD, 4811, Australia.
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, 4811, Australia.
- German Centre for Integrative Biodiversity Research (IDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, Leipzig, 04103, Germany.
| | - Morgan S Pratchett
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, 4811, Australia
| | - Sean R Connolly
- Marine Biology and Aquaculture, College of Science and Engineering, James Cook University, Townsville, QLD, 4811, Australia
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, 4811, Australia
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12
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Martin PR, Freshwater C, Ghalambor CK. The outcomes of most aggressive interactions among closely related bird species are asymmetric. PeerJ 2017; 5:e2847. [PMID: 28070465 PMCID: PMC5217525 DOI: 10.7717/peerj.2847] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 11/30/2016] [Indexed: 11/20/2022] Open
Abstract
Aggressive interactions among closely related species are common, and can play an important role as a selective pressure shaping species traits and assemblages. The nature of this selective pressure depends on whether the outcomes of aggressive contests are asymmetric between species (i.e., one species is consistently dominant), yet few studies have estimated the prevalence of asymmetric versus symmetric outcomes to aggressive contests. Here we use previously published data involving 26,212 interactions between 270 species pairs of birds from 26 taxonomic families to address the question: How often are aggressive interactions among closely related bird species asymmetric? We define asymmetry using (i) the proportion of contests won by one species, and (ii) statistical tests for asymmetric outcomes of aggressive contests. We calculate these asymmetries using data summed across different sites for each species pair, and compare results to asymmetries calculated using data separated by location. We find that 80% of species pairs had aggressive outcomes where one species won 80% or more of aggressive contests. We also find that the majority of aggressive interactions among closely related species show statistically significant asymmetries, and above a sample size of 52 interactions, all outcomes are asymmetric following binomial tests. Species pairs with dominance data from multiple sites showed the same dominance relationship across locations in 93% of the species pairs. Overall, our results suggest that the outcome of aggressive interactions among closely related species are usually consistent and asymmetric, and should thus favor ecological and evolutionary strategies specific to the position of a species within a dominance hierarchy.
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Affiliation(s)
- Paul R Martin
- Department of Biology, Queen's University , Kingston , Ontario , Canada
| | - Cameron Freshwater
- Department of Biology, University of Victoria , Victoria , British Columbia , Canada
| | - Cameron K Ghalambor
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University , Fort Collins , Colorado , United States
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13
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Freshwater C, Ghalambor CK, Martin PR. Repeated patterns of trait divergence between closely related dominant and subordinate bird species. Ecology 2014; 95:2334-45. [PMID: 25230483 DOI: 10.1890/13-2016.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Ecologically similar species often compete aggressively for shared resources. These interactions are frequently asymmetric, with one species behaviorally dominant to another and excluding it from preferred resources. Despite the potential importance of this type of interference competition as a source of selection, we know little about patterns of trait divergence between dominant and subordinate species. We compiled published data on phylogenetically independent, closely related species of North American birds where one species was consistently dominant in aggressive interactions with a congeneric species. We then compared the body size, breeding phenology, life history, ecological breadth, and biogeography of these species. After accounting for body size and phylogeny, we found repeated patterns of trait divergence between subordinate and dominant species within genera. Subordinate species that migrated seasonally arrived 4-7 days later than dominants on their sympatric breeding grounds, and both resident and migratory subordinates initiated breeding 7-8 days later than their dominant, sympatric congeners. Subordinate species had a 5.2% higher annual adult mortality rate and laid eggs that were 0.02 g heavier for their body mass. Dominant and subordinate species used a similar number of different foods, foraging behaviors, nest sites, and habitats, but subordinates were more specialized in their foraging behaviors compared with closely related dominant species. The breeding and wintering ranges of subordinate species were 571 km farther apart than the ranges of dominant species, suggesting that subordinate species migrate greater distances. Range sizes and latitudinal distributions did not consistently differ, although subordinate species tended to breed farther north or winter farther south. These results are consistent with dominant species directly influencing the ecological strategies of subordinate species (via plastic or genetically based changes), either by restricting their access to resources or simply through aggression. Alternatively, these ecological traits may covary with patterns of behavioral dominance, with no direct consequences of interactions. Regardless of the mechanism, recognizing that the relative position of a species within a dominance hierarchy is correlated with a suite of other ecological and fitness related traits has far-reaching implications for the mechanisms underlying species distributions and the structure of biological assemblages.
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14
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Pratchett MS, Hoey AS, Cvitanovic C, Hobbs JPA, Fulton CJ. Abundance, diversity, and feeding behavior of coral reef butterflyfishes at Lord Howe Island. Ecol Evol 2014; 4:3612-25. [PMID: 25478152 PMCID: PMC4224535 DOI: 10.1002/ece3.1208] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 07/24/2014] [Accepted: 07/25/2014] [Indexed: 11/30/2022] Open
Abstract
Endemic species are assumed to have a high risk of extinction because their restricted geographic range is often associated with low abundance and high ecological specialization. This study examines the abundance of Chaetodon butterflyfishes at Lord Howe Island in the south-west Pacific, and compares interspecific differences in local abundance to the feeding behavior and geographic range of these species. Contrary to expected correlations between abundance and geographic range, the single most abundant species of butterflyfish was Chaetodon tricinctus, which is endemic to Lord Howe Island and adjacent reefs; densities of C. tricinctus (14.1 ± 2.1 SE fish per 200m2) were >3 times higher than the next most abundant butterflyfish (Chaetodon melannotus), and even more abundant than many other geographically widespread species. Dietary breadth for the five dominant butterflyfishes at Lord Howe Island was weakly and generally negative correlated with abundance. The endemic C. tricinctus was a distinct outlier in this relationship, though our extensive feeding observations suggest some issues with the measurements of dietary breadth for this species. Field observations revealed that all bites taken on benthic substrates by C. tricinctus were from scleractinian corals, but adults rarely, if ever, took bites from the benthos, suggesting that they may be feeding nocturnally and/or using mid-water prey, such as plankton. Alternatively, the energetic demands of C. tricinctus may be fundamentally different to other coral-feeding butterflyfishes. Neither dietary specialization nor geographic range accounts for interspecific variation in abundance of coral reef butterflyfishes at Lord Howe Island, while much more work on the foraging behavior and population dynamics of C. tricinctus will be required to understand its’ abundance at this location.
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Affiliation(s)
- Morgan S Pratchett
- ARC Centre of Excellence for Coral Reef Studies, James Cook University Townsville, Queensland, 4811, Australia
| | - Andrew S Hoey
- ARC Centre of Excellence for Coral Reef Studies, James Cook University Townsville, Queensland, 4811, Australia
| | - Christopher Cvitanovic
- Oceans and Atmosphere Flagship, CSIRO Hobart, Tasmania, 7000, Australia ; ARC Centre of Excellence for Coral Reef Studies, Research School of Biology, Australian National University Canberra, Australian Capital Territory, 0200, Australia
| | - Jean-Paul A Hobbs
- Department of Environment and Agriculture, Curtin University Perth, Western Australia, 6845, Australia
| | - Christopher J Fulton
- ARC Centre of Excellence for Coral Reef Studies, Research School of Biology, Australian National University Canberra, Australian Capital Territory, 0200, Australia
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